ImmunoGen, Inc. (Nasdaq: IMGN), a biopharmaceutical company that develops targeted anticancer therapeutics, today announced the presentation of encouraging trastuzumab-DM1 (T-DM1) clinical data at the 2009 Annual Meeting of the American Society of Clinical Oncology (ASCO) taking place in Orlando, Florida.

T-DM1, an antibody-drug conjugate, consists of ImmunoGen’s DM1 cancer-cell killing agent linked to the HER2-targeted antibody, trastuzumab, developed by Genentech, Inc. (a wholly-owned member of the Roche Group). Genentech (US) and Roche (ex-US) are conducting a broad clinical program with T-DM1 in HER2-positive breast cancer.

“These findings are particularly impressive because of the number of patients with advanced breast cancer who responded to treatment with T-DM1, the duration of their response, and the tolerability profile reported,” commented Daniel Junius, President and Chief Executive Officer. “We developed our Targeted Antibody Payload, or TAP, technology to achieve highly effective, well-tolerated cancer treatments, and are very encouraged by the results reported.”

Today’s presentation, “A phase II study of trastuzumab-DM1 (T-DM1), a HER2 antibody-drug conjugate (ADC), in patients with HER2+ metastatic breast cancer (MBC): final results” (abstract #1017), features updated data from the first T-DM1 Phase II trial. This non-pivotal trial evaluated T-DM1 in patients with HER2-positive MBC that had progressed on a regimen containing trastuzumab (Herceptin^®). Sixty percent of the 112 study patients also had been treated with a regimen containing lapatinib (Tykerb^®).

Among the findings presented were:

• 25 percent of patients had a confirmed objective response as assessed by an independent review facility (IRF), the primary endpoint of the study.